Unit 7 Biology Study Guide

Describe how DNA differs from RNA

• Be able to identify the structure of each nucleic acid.

  • Type of sugar, 

    • DNA (Deoxyribose Sugar)

    • RNA (Ribose Sugar)

  • Type(s) of nitrogen bases

    • DNA

      • Adenine (A)  Thymine (T)

      • Guanine (G)  Cytosine (C)

    • RNA

      • Adenine (A)  Uracil (U)

      • Guanine (G)  Cytosine (C)

  • Number of strands in molecule

    • DNA = Double Stranded

    • RNA = Single stranded

  • Role each plays in protein synthesis

    • DNA = Transcription template 

      • Stores genetic information that provides blueprints for building proteins

    • RNA = Many roles

      • Messenger RNA (mRNA)

        • Carries genetic instructions from the DNA to the ribosome

      • Ribosomal RNA (rRNA)

        • Forms the core structure of ribosomes

      • Transfer RNA (tRNA)

        • Delivers amino acids to the ribosome

  • Build/draw a nucleotide of each molecule.

  • Where each molecule is found in a eukaryotic cell

    • DNA = Founded in the NUCLEUS MOSTLY

      • (Little of DNA is founded in the mitochondria)

    • RNA = Founded in the nucleus and the Cytoplasm

Be able to explain and draw the process of transcription.

• Be able to explain/draw the step by step process of taking the DNA code to mRNA.

  • Know the location in a eukaryotic cell.

    • Taking the DNA code to mRNA occurs in the NUCLEUS and transcribes it to the cytoplasm

  • Describe the role of RNA Polymerase.

    • RNA Polymerase turns DNA into Messenger RNA (mRNA)

  • Describe the role of mRNA and DNA.

    • mRNA = Carries the genetic code from the DNA to the ribosome in the cytoplasm where proteins are synthesized 

    • DNA = Stores genetic information and acts as a template for mRNA during transcription

  • Given a piece of DNA be able produce a mRNA sequence with 100% accuracy.

    • AGC CTA GCC AAT (DNA)

    • UCG GAU CGG UUA (mRNA)

Be able to explain and draw the process of translation (mRNA → Protein).

• Be able to explain/draw the step by step process of taking mRNA to protein.

  • Know the location in a eukaryotic cell.

    • Happens in the CYTOPLASM

• Describe the role of following:

• Ribosomes

  • Builds/assembles amino acids into polypeptides based on mRNA sequence

• tRNA

  • Brings amino acids to the ribosome, matching the mRNA codons with its anticodons

• Codon

  • Sequence of three nucleotides in mRNA that code for a specific amino acid

• Anticodon

  • Sequence of three nucleotides in tRNA that is complementary (opposite) to the mRNA codon.

• Amino Acids

  • Building blocks of proteins and are assembled into a polypeptide chain

• Polypeptide Chain

  • A long chain of amino acids that fold into a protein

Explain how mutations affect the expression of the genes. (phenotype, protein, etc.). 

• Be able to identify/define the following mutations given a piece of DNA or mRNA

  • Understand the following vocabulary: 

    • DNA Mutations

      • Point Mutation/Base Substitution

        • One nucleotide base is replaced by another

      • Insertion

        • One or more nucleotide bases are added to the DNA or RNA sequence.  (Affects rest of sequence)

      • Deletion

        • One or more nucleotide bases are removed from a DNA or RNA sequence.  (Affects rest of sequence)

    • Protein Changes

      • Frameshift

        • Caused by insertion or deletion and altering the rest of the amino acid sequence

      • Samesence (silent) , missense, nonsense

        • Silent

          • Mutation where a nucleotide change does not alter the amino acid sequence

        • Missense

          • Mutation where a nucleotide change alters the codon resulting in a different amino acid being created for the protein

        • Nonsense

          • Mutation where a nucleotide changes to a STOP codon and ending the mRNA sequence

  • Be able to identify/describe how each mutation can impact the expression of the gene.

    • How it impacts the amino acid sequence.

    • How it impacts the folding of the protein (remember, proteins have to have the correct shape to do their function)

    • How it impacts the phenotype (physical features or function) of the individual.

Mutation Type Amino Acid Sequence Impact Protein Folding Impact Phenotype Impact

Silent No change No effect No effect (rarely affects splicing)

Missense One amino acid substituted May disrupt or preserve folding Mild to severe (depends on amino acid change)

Nonsense Early stop codon (truncated protein) Usually misfolded/nonfunctional Severe (loss of essential protein function)

Insertion Extra amino acids (or frameshift) May disrupt folding if large Mild to severe (depends on insertion size)

Deletion Missing amino acids (or frameshift) May misfold if structural regions are lost Mild to severe (depends on gene and location)

Frameshift Entire downstream sequence altered Often catastrophic misfolding Severe (usually loss of function)

Silent = No effects  Missense = Little effects  Nonsense = Bad effects